Hi,
Download Recover My Files v4 beta here:
Recover My Files v4 Beta Testing Page - run a Disk recovery on the physical drive. This should find your entire file and folder stucture.
Because the drive is so big, you dont need to let the search run all the way to the end. Keep an eye on the "Filesystem" records number near the progress bar, and when it gets to a high number and stops increasing (each one represents a file) then press the stop button. You should get to this point within a 2 hour search.
Please let me know how it goes.